1. Field of the Invention
The present invention relates to electrical connectors and methods of making the same.
2. Related Art
Electrical connectors with the connection sections of contact elements soldered to a circuit board or the like are designed such that the connection sections project from the housing by a constant length. The connection sections are provided on circuit traces of the circuit board, a cream or paste-like solder is applied, and the connection sections are soldered simultaneously. Alternatively, solder balls are provided as connection sections. That is, the solder balls are provided on circuit traces and heated to melt for soldering.
The contact elements are made to a single size but always involved with manufacturing errors. In addition, there are errors in installation into the housing, manufacturing the housing, and warping of the housing. These errors are added up to put the connection sections of contact elements on different planes, making poor soldering or failing to provide uniform soldering for the contact sections which are not contacted but spaced from the circuit traces. Similarly, the solder balls make uneven contact with the circuit traces so that the solder balls suffer from uneven heating conditions, resulting in the poor or uneven soldering.
Accordingly, it is an object of the invention to provide an electrical connector having contact elements whose connection sections make even contact with the same surface regardless of errors of the contact elements and the housing.
According to one aspect of the invention there is provided an electrical connector which comprises a housing; a plurality of contact elements attached to said housing such that connection sections thereof project from said housing; a plurality of solder portions provided on front ends of said connection sections and having regular surfaces which are positioned on a single plane.
Since the solder portions of a plurality of contact elements have regular surfaces which are disposed on a single plane and make even contact with corresponding circuit traces, poor or uneven soldering is prevented. The regular surfaces may be flat or curved.
According to another aspect of the invention there is provided a method of making an electrical connector with a plurality of contact elements having connection sections projecting from said housing, which comprises the steps of forming a plurality of regular recesses in an upper face of a mold member; filling said regular recesses with solder; putting front ends of said connection sections into said solder in said regular recesses; solidifying said solder; and removing said connection sections from said mold member.
According to still another aspect of the invention there is provided a method of making an electrical connector with a plurality of contact elements having connection sections projecting from said housing, which comprises the steps of applying solder to front ends of said connection sections; pressing said front ends with solder against a base surface; solidifying said solder; and removing said connection sections from said base surface.
Alternatively, the pressing step is replaced by pressing said front ends with solder against a base surface to melt said solder by heat of said base surface.
According to yet another aspect of the invention there is provided a method of making an electrical connector with a plurality of contact elements having connection sections projecting from said housing, which comprises the steps of simultaneously putting front ends of said connection sections into a melted solder in a soldering tank; pulling said front ends of said connection sections out of said melted solder to form solder masses adhered to said front ends of said connection sections; pressing said solder masses of said connection sections against a base surface; solidifying said solder masses; and removing said solder masses of said connection sections from said base surface.
The connection sections prior to formation of the solder portions may take any shape but the shape to which melted solder adheres readily and the solidified solder firmly adhered is preferred.